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                                                                    EXHIBIT 10.1

                 RENEWAL REVOLVING CO-BORROWER PROMISSORY NOTE

$2,500,000.00                                               Due December 5, 2002
                                                          Minneapolis, Minnesota


                                                  Dated as of January 29th, 2002


On December 5, 2002, the undersigned, for value received, jointly and severally
promise to pay to the order of Associated Bank Minnesota (the "Bank"), at its
main office in Minneapolis, Minnesota in lawful money of the United States of
America, the principal sum of Two Million Five Hundred Thousand and no/100
Dollars ($2,500,000.00), or so much thereof as is advanced and remains
outstanding hereunder on the due date as shown on the Bank's liability record,
together with interest (computed on the basis of actual days elapsed in a 360 -
day year) thereon from the date hereof until fully paid at an annual rate equal
on each day to 1.0% above the U.S. Prime Rate reported by the Wall Street
Journal on that day or the immediately preceding business day or, if the Wall
Street Journal does not report such a rate on that day, as reported by any
other national financial publication selected by the Bank. Each change in the
interest rate hereon shall become effective on the day the corresponding change
in the Prime Rate is reported, but in no event shall the interest rate under
this Note be less than 6.0%.

The undersigned consist of Quantech Ltd. (the "Entity Borrower") and Richard W.
Perkins, Richard W. Perkins as Trustee of the Richard W. Perkins Revocable
Trust Established Under Agreement Dated June 14, 1978, James F. Lyons, James F.
Lyons as Trustee of the James F. Lyons Revocable Trust Established Under
Agreement Dated April 18, 2000, Edward E. Strickland and Robert W. Gaines (each
an "Individual Borrower" and, together with the Entity Borrower, the
"Borrowers"). Each Borrower is a co-borrower under this Note and each is
fully obligated for the entire principal balance of this Note regardless of
how, or at whose request, the Bank disburses the proceeds of this Note. Each of
the undersigned acknowledges that each is directly obligated as a borrower
under this Note and that none of the undersigned has signed in an accommodation
capacity.

Advances under this Note are available from time to time in the absence of an
Event of Default in an aggregate amount not to exceed $2,500,000.00. The
undersigned may borrow, pre-pay (without premium or penalty) and re-borrow
under this Note subject to the terms of this Note.

Interest shall be payable monthly on the last day of each month and at maturity.

Each of the Entity Borrower, Perkins and Partners Profit Sharing Plan and
Trust, James F. Lyons as Trustee of the James F. Lyons Revocable Trust
Established Under Agreement Dated April 18, 2000, Edward E. Strickland and
Robert W. Gaines has provided collateral for this Note pursuant to a Pledge
Agreement (collectively, the "Pledge Agreements") dated on or about the date of
this Note.

Each of the following events shall constitute an Event of Default under this
Note:



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      1.   If the undersigned shall fail to perform any of their obligations
           under this Note;

      2.   If any payment due on any other indebtedness to the Bank of any of
           the undersigned is not paid within 45 days after the due date for
           that payment;

      3.   If a garnishment summons or a writ of attachment is issued against
           or served upon the Bank for the attachment of any property of any of
           the undersigned in the Bank's possession or any indebtedness owing to
           any of the undersigned;

      4.   If any of the undersigned shall submit to the Bank any credit
           application or financial statement containing information which shall
           prove to be incorrect in any material respect when made;

      5.   If any of the undersigned shall fail to pay when due any material
           indebtedness for borrowed money, or, if such indebtedness is subject
           to a cure period, by the end of the cure period;

      6.   If a petition is filed by or against any of the undersigned under the
           United States Bankruptcy Code, or if a trustee, receiver or similar
           officer is appointed for any of the undersigned or for the property
           of any of the undersigned;

      7.   If any of the undersigned shall fail to provide annual financial
           statements (audited in the case of the Entity Borrower) and tax
           returns to the Bank;

      8.   If the Entity Borrower shall fail to provide monthly unaudited
           financial statements to the Bank within 30 days after the end of each
           month;

      9.   If the aggregate fair market value of the liquid assets subject to a
           first priority security interest in favor of the Bank pursuant to the
           Pledge Agreements is less than $3,000,000.00 at any time.

Upon any Event of Default, the undersigned shall have no further right to
request advances under this Note and, if the Event of Default is not cured
within 30 days, the Bank may, at its option, declare this Note to be
immediately payable, together with all unpaid interest accrued hereon, without
notice or demand and may exercise any other right available to the Bank. No
cure period shall apply to an Event of Default under Paragraph 6 above and this
Note shall immediately become due and payable upon such an Event of Default.

If this Note is not paid when due, either on the due date or upon acceleration,
the Bank shall have the right to set off the indebtedness evidenced by this
Note against any indebtedness of the Bank to any of the undersigned.

The Bank may at any time renew this Note or extend its maturity date for any
period and release any security for, or any party to, this Note, all without
notice to or consent of and without releasing any accommodation maker, endorser
or guarantor. The undersigned agree,



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jointly and severally, to pay all costs of collection, including attorneys'
fees and legal expenses, in the event this Note is not paid when due whether
suit is commenced or not, including costs and expenses in litigation,
bankruptcy or insolvency proceedings. Presentment or other demand for payment,
notice of dishonor and protest are hereby waived by the undersigned. This Note
shall be governed by the substantive laws of the State of Minnesota. The
undersigned hereby irrevocably submit to the jurisdiction of the Minnesota
District Court, Fourth District, and the Federal District Court, District of
Minnesota, Fourth Division, over any action or proceeding arising out of or
relating to this Note and agree that all claims in respect of such action or
proceeding may be heard and determined in any such court.

This Note may be signed by the undersigned in one or more counterparts,
including facsimile counterparts, all of which counterparts taken together
shall constitute a single document. The failure of one or more of the named
parties to sign this Note shall not affect the obligations of those parties who
do sign this Note.

This Note is a renewal and replacement of a $2,500,000.00 promissory note dated
as of May 17, 2001 from the undersigned to the Bank which prior note remains
unpaid but the principal balance of which has been incorporated into this Note.
It is an express condition to the renewal of the prior note that the
undersigned have paid to the Bank a renewal fee of $25,000.00.

Quantech, Ltd.


By /s/ James F. Lyons                      /s/ Richard W. Perkins
   -----------------------------------     ------------------------------------
   James F. Lyons                          Richard W. Perkins (Individually)
   Its President


   /s/ Richard W. Perkins                  /s/ James F. Lyons
   ------------------------------------    -------------------------------------
   Richard W. Perkins as Trustee of the    James F. Lyons (Individually)
   Richard W. Perkins Revocable Trust
   Established Under Agreement Dated
   June 14, 1978


   /s/ James F. Lyons                      /s/ Edward E. Strickland
   ------------------------------------    -------------------------------------
   James F. Lyons as Trustee of the        Edward E. Strickland (Individually)
   James F. Lyons Revocable Trust
   Established Under Agreement Dated
   April 18, 2000

                                           /s/ Robert W. Gaines
                                           -------------------------------------
                                           Robert W. Gaines (Individually)




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